xref: /dragonfly/lib/libc/locale/mbrtowc.3 (revision 6ca88057) 
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25.\" $FreeBSD: head/lib/libc/locale/mbrtowc.3 250883 2013-05-21 19:59:37Z ed $
26.\"
27.Dd December 26, 2013
28.Dt MBRTOWC 3
29.Os
30.Sh NAME
31.Nm mbrtowc ,
32.Nm mbrtowc_l ,
33.Nm mbrtoc16 ,
34.Nm mbrtoc32
35.Nd "convert a character to a wide-character code (restartable)"
36.Sh LIBRARY
37.Lb libc
38.Sh SYNOPSIS
39.In wchar.h
40.Ft size_t
41.Fo mbrtowc
42.Fa "wchar_t * restrict pc" "const char * restrict s" "size_t n"
43.Fa "mbstate_t * restrict ps"
44.Fc
45.In uchar.h
46.Ft size_t
47.Fo mbrtoc16
48.Fa "char16_t * restrict pc" "const char * restrict s" "size_t n"
49.Fa "mbstate_t * restrict ps"
50.Fc
51.Ft size_t
52.Fo mbrtoc32
53.Fa "char32_t * restrict pc" "const char * restrict s" "size_t n"
54.Fa "mbstate_t * restrict ps"
55.Fc
56.In xlocale.h
57.Ft size_t
58.Fo mbrtowc_l
59.Fa "wchar_t * restrict pc" "const char * restrict s" "size_t n"
60.Fa "mbstate_t * restrict ps" "locale_t locale"
61.Fc
62.Sh DESCRIPTION
63The
64.Fn mbrtowc ,
65.Fn mbrtowc_l ,
66.Fn mbrtoc16
67and
68.Fn mbrtoc32
69functions inspect at most
70.Fa n
71bytes pointed to by
72.Fa s
73to determine the number of bytes needed to complete the next multibyte
74character.
75If a character can be completed, and
76.Fa pc
77is not
78.Dv NULL ,
79the wide character which is represented by
80.Fa s
81is stored in the
82.Vt wchar_t ,
83.Vt char16_t
84or
85.Vt char32_t
86it points to.
87.Pp
88If
89.Fa s
90is
91.Dv NULL ,
92these functions behave as if
93.Fa pc
94was
95.Dv NULL ,
96.Fa s
97was an empty string
98.Pq Qq
99and
100.Fa n
101was 1.
102.Pp
103The
104.Vt mbstate_t
105argument,
106.Fa ps ,
107is used to keep track of the shift state.
108If it is
109.Dv NULL ,
110these functions use an internal, static
111.Vt mbstate_t
112object, which is initialized to the initial conversion state
113at program startup.
114.Pp
115As a single
116.Vt char16_t
117is not large enough to represent certain multibyte characters, the
118.Fn mbrtoc16
119function may need to be invoked multiple times to convert a single
120multibyte character sequence.
121.Pp
122The
123.Fn mbrtowc_l
124function takes an explicit
125.Fa locale
126argument, whereas the
127.Fn mbrtowc
128function uses the current global or per-thread locale.
129.Sh RETURN VALUES
130The
131.Fn mbrtowc ,
132.Fn mbrtowc_l ,
133.Fn mbrtoc16
134and
135.Fn mbrtoc32
136functions return:
137.Bl -tag -width indent
138.It 0
139The next
140.Fa n
141or fewer bytes
142represent the null wide character
143.Pq Li "L'\e0'" .
144.It >0
145The next
146.Fa n
147or fewer bytes represent a valid character, these functions
148return the number of bytes used to complete the multibyte character.
149.It Po Vt size_t Pc Ns \-1
150An encoding error has occurred.
151The next
152.Fa n
153or fewer bytes do not contribute to a valid multibyte character.
154.It Po Vt size_t Pc Ns \-2
155The next
156.Fa n
157contribute to, but do not complete, a valid multibyte character sequence,
158and all
159.Fa n
160bytes have been processed.
161.El
162.Pp
163The
164.Fn mbrtoc16
165function also returns:
166.Bl -tag -width indent
167.It Po Vt size_t Pc Ns \-3
168The next character resulting from a previous call has been stored.
169No bytes from the input have been consumed.
170.El
171.Sh ERRORS
172The
173.Fn mbrtowc ,
174.Fn mbrtowc_l ,
175.Fn mbrtoc16
176and
177.Fn mbrtoc32
178functions will fail if:
179.Bl -tag -width Er
180.It Bq Er EILSEQ
181An invalid multibyte sequence was detected.
182.It Bq Er EINVAL
183The conversion state is invalid.
184.El
185.Sh SEE ALSO
186.Xr mbtowc 3 ,
187.Xr multibyte 3 ,
188.Xr setlocale 3 ,
189.Xr wcrtomb 3 ,
190.Xr xlocale 3
191.Sh STANDARDS
192The
193.Fn mbrtowc ,
194.Fn mbrtoc16
195and
196.Fn mbrtoc32
197functions conform to
198.St -isoC-2011 .
199